In drilling wells for oil and gas exploration, understanding the structure and properties of the associated geological formation provides information to aid such exploration. Logging measurements may be performed in a borehole to obtain this information. However, the environment in which the drilling tools operate and where measurements are made may be located at significant distances below the surface. It may be desirable to transmit downhole logging measurements to the surface for analysis and control purposes.
Electrical cables have been investigated for high speed telemetry to and from downhole tools. Use of electrical cables for such communication, however, has drawbacks due to limitations with information bandwidth. Optical fibers have also been investigated for high speed communications to and from downhole tools to overcome the information bandwidth limitations of electrical cables. However, stresses imposed on the optical fiber in the downhole environment may cause a change in the light polarization by the time it reaches the surface. This may cause a loss of signal at the surface polarizer and, thus, a loss of data.